University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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James E. Atwater

Abbrev:
Atwater, J.E.
Other Names:
Address:
UMPQUA Research Company, PO Box 609, Myrtle Creek, OR 97457, USA
Phone:
NA
Fax:
NA

Citations 4

"Reagentless Flow Injection Determination Of Ammonia And Urea Using Membrane Separation And Solid Phase Basification"
Microchem. J. 1998 Volume 59, Issue 3 Pages 372-382
James R. Akse, John O. Thompson, Richard L. Sauer and James E. Atwater

Abstract: Flow injection analysis instrumentation and methodology for the determination of NH3 and ammonium ions in an aqueous solution are described. Using inline solid phase basification beds containing crystalline media, the speciation of ammoniacal N is shifted toward the un-ionized form, which diffuses in the gas phase across a hydrophobic microporous hollow fiber membrane into a pure-H2O-containing analysis stream. The two streams flow in a countercurrent configuration on opposite sides of the membrane. The neutral pH of the analysis stream promotes the formation of ammonium cations, which are detected using specific conductance. The methodology provides a lower limit of detection of 10 µg/L and a dynamic concentration. range spanning three orders of magnitude using a 315 µL sample injection volume Using immobilized urease to enzymatically promote the hydrolysis of urea to produce NH3 and CO2, the technique was extended to the determination of urea.
Ammonia Urea Waste Conductometry Gas diffusion Immobilized reagent Microporous membrane Solid phase reagent

"Dissolved Oxygen Determination By Electrocatalysed Chemiluminescence With Inline Solid Phase Media"
J. Biolumin. Chemilumin. 1998 Volume 13, Issue 3 Pages 125-130
James E. Atwater*, Jeffrey DeHart, Richard R. Wheeler Jr

Abstract: Dissolved elemental oxygen is determined in a flowing aqueous stream using glucose oxidase to catalyse the reaction between D-glucose and O-2 to produce hydrogen peroxide. The revels of the resulting H2O2 are detected and quantified by luminol chemiluminescence using inline solid phase media for pH adjustment of the reagent stream and for controlled release of the luminophore. The reaction is initiated by electrochemical catalysis. By the use of excess D-glucose in the reagent flow stream, the intensity of chemiluminescence is rendered proportional only to fluctuations in the dissolved O-2 concentration. The methodology provides a means for the detection of aqueous O-2 in the range 0-10 mg/L.
Oxygen Chemiluminescence Solid phase reagent pH

"Enzymic Determination Of Ethanol Using 'reagentless' Electrocatalyzed Luminol Chemiluminescence"
Anal. Lett. 1997 Volume 30, Issue 8 Pages 1445-1453
NAJames E. Atwater; James R. Akse; Jeffrey DeHart; Richard R. Wheeler Jr.

Abstract: The carrier stream comprised water (4.5 ml/min) flowing sequentially through a 2.5 mL solid-phase basification (SPB) bed, a 0.5 mL crystallized luminol bed and a 5 mL SPB bed. The resulting carrier stream comprised 50 mg/l luminol of pH 10.3. The sample stream consisted of water, equilibrated with atmospheric O2 containing aqueous ethanol was passed through a 1.2 mL immobilized alcohol oxidase bed at a rate of 3 ml/min corresponding to a carrier stream-to-analyte stream flow ratio of 3:2. The carrier and analyte streams were mixed at the inlet of the electrocatalyzed chemiluminescence cell. The intensity of the resulting chemiluminescence was measured by a photomultiplier tube. The method was suitable for the determination of aqueous ethanol concentrations ranging from 3-340 µM.
Ethanol Water Chemiluminescence Column Solid phase reagent Electrochemical product conversion Immobilized enzyme

"'Reagentless' Flow Analysis Determination Of Hydrogen Peroxide By Electrocatalysed Luminol Chemiluminescence"
Anal. Lett. 1997 Volume 30, Issue 1 Pages 21-31
James E. Atwater; James R. Akse; Jeffery DeHart; Richard R. Wheeler Jr.

Abstract: A schematic diagram is shown of the flow system. water carrier stream was passed sequentially through a 2.5 mL solid-phase basification (SPB) bed, a 0.5 mL crystallized luminol bed and a 5 mL SPB bed. The resulting carrier stream contained 50 mg/l of luminol of pH 10.3 and was mixed with the sample stream (3:2) just before the electrochemiluminescence cell. The chemiluminescence reaction was electrocatalyzed by a potential of ~0.6 V with a Au foil working electrode, a Au mesh counter electrode and a Ag/AgCl reference electrode. The calibration range extended from 0.033-16.65 mg/l of H2O2 (graph shown). The method should be applicable to both continuous-flow and flow injection systems.
Hydrogen peroxide Chemiluminescence Electrode Column Solid phase reagent Electrochemical product conversion